During a humanitarian mission to southeast Asia, a 42-year-old man is brought to the outpatient clinic for a long history (greater than 2 years) of progressive, painless, enlargement of his scrotum. The family history is negative for malignancies and inheritable diseases. The personal history is relevant for cigarette smoking (up to 2 packs per day for the last 20 years) and several medical consultations for an episodic fever that resolved spontaneously. The physical examination is unremarkable, except for an enlarged left hemiscrotum that transilluminates. Which of the following accounts for the underlying mechanism in this patient's condition?
Q12
A 19-year-old man is brought to the emergency department following a high-speed motor vehicle collision in which he was a restrained passenger. He complains of pelvic pain and urinary retention with overflow incontinence, along with associated lower extremity weakness. Examination shows perineal bruising and there is pain with manual compression of the pelvis. Injury to which of the following structures is most likely responsible for this patient's urinary incontinence?
Q13
A 53-year-old multiparous woman is scheduled to undergo elective sling surgery for treatment of stress incontinence. She has frequent loss of small amounts of urine when she coughs or laughs, despite attempts at conservative treatment. The physician inserts trocars in the obturator foramen bilaterally to make the incision and passes a mesh around the pubic bones and underneath the urethra to form a sling. During the procedure, the physician accidentally injures a nerve in the obturator foramen. The function of which of the following muscles is most likely to be affected following the procedure?
Q14
A 60-year-old post-menopausal female presents to her gynecologist with vaginal bleeding. Her last period was over 10 years ago. Dilation and curettage reveals endometrial carcinoma so she is scheduled to undergo a total abdominal hysterectomy and bilateral salpingo-oophorectomy. During surgery, the gynecologist visualizes paired fibrous structures arising from the cervix and attaching to the lateral pelvic walls at the level of the ischial spines. Which of the following vessels is found within each of the paired visualized structure?
Q15
A 56-year-old man comes to the clinic complaining of sexual dysfunction. He reports normal sexual function until 4 months ago when his relationship with his wife became stressful due to a death in the family. When asked about the details of his dysfunction, he claims that he is “able to get it up, but just can’t finish the job.” He denies any decrease in libido or erections, endorses morning erections, but an inability to ejaculate. He is an avid cyclist and exercises regularly. His past medical history includes depression and diabetes, for which he takes citalopram and metformin, respectively. A physical examination is unremarkable. What is the most likely explanation for this patient’s symptoms?
Q16
A 26-year-old woman presents to the obstetrics ward to deliver her baby. The obstetrician establishes a pudendal nerve block via intravaginal injection of lidocaine near the tip of the ischial spine. From which of the following nerve roots does the pudendal nerve originate?
Q17
A 67-year-old man comes to the physician because of a 3-month history of difficulty initiating urination. He wakes up at least 3–4 times at night to urinate. Digital rectal examination shows a symmetrically enlarged, nontender prostate with a rubbery consistency. Laboratory studies show a prostate-specific antigen level of 2.1 ng/mL (N < 4). Which of the following is the most likely underlying cause of this patient's symptoms?
Q18
A 55-year-old man comes to the physician because of a 2-day history of severe perianal pain and bright red blood in his stool. Examination shows a bulging, red nodule at the rim of the anal opening. Which of the following arteries is the most likely source of blood to the mass found during examination?
Q19
A 73-year-old man comes to the physician because of a 2-month history of intermittent blood in his stool. He has had no pain with defecation. Physical examination shows a 2-cm mass located above the dentate line. Further evaluation of the mass confirms adenocarcinoma. Which of the following describes the most likely route of hematogenous spread of the malignancy?
Q20
A 70-year-old woman comes to the physician for a follow-up examination 2 months after undergoing a total hip replacement surgery. She reports that she has persistent difficulty in walking since the surgery despite regular physiotherapy. Examination of her gait shows sagging of the left pelvis when her right leg is weight-bearing. Which of the following nerves is most likely to have been injured in this patient?
Pelvis/Perineum US Medical PG Practice Questions and MCQs
Question 11: During a humanitarian mission to southeast Asia, a 42-year-old man is brought to the outpatient clinic for a long history (greater than 2 years) of progressive, painless, enlargement of his scrotum. The family history is negative for malignancies and inheritable diseases. The personal history is relevant for cigarette smoking (up to 2 packs per day for the last 20 years) and several medical consultations for an episodic fever that resolved spontaneously. The physical examination is unremarkable, except for an enlarged left hemiscrotum that transilluminates. Which of the following accounts for the underlying mechanism in this patient's condition?
A. Idiopathic
B. Invasive neoplasm
C. Decreased lymphatic fluid absorption (Correct Answer)
D. Autoimmune
E. Patent processus vaginalis
Explanation: ***Decreased lymphatic fluid absorption***
- The patient's history of **episodic fever** in Southeast Asia strongly suggests **filariasis**, an endemic parasitic infection that can cause **lymphatic obstruction**.
- **Chronic lymphatic obstruction** leads to decreased lymphatic fluid absorption, causing **hydrocele** (fluid accumulation in the scrotum) and **lymphedema**, which explains the **progressive, painless scrotal enlargement** that **transilluminates**.
*Idiopathic*
- While some hydroceles are idiopathic, the patient's history of **episodic fever** and residence in an **endemic area** for filariasis suggests a specific underlying cause, making it less likely to be idiopathic.
- Idiopathic hydroceles typically lack a clear precipitating event or association with systemic symptoms like recurrent fevers.
*Invasive neoplasm*
- An **invasive neoplasm** would typically present as a **solid, non-transilluminating mass** and often be associated with other symptoms like weight loss or pain.
- The **transillumination** of the scrotal enlargement indicates a fluid collection, making a solid tumor less likely.
*Autoimmune*
- Autoimmune conditions rarely present with isolated, progressive, painless scrotal enlargement and transillumination.
- Systemic autoimmune diseases typically involve multiple organ systems and present with a different constellation of symptoms, such as joint pain, rash, or fatigue.
*Patent processus vaginalis*
- A **patent processus vaginalis** is a common cause of **communicating hydrocele**, typically presenting in **infancy or early childhood**.
- In adults, it is a less common cause of new-onset hydrocele, and it would not explain the history of **episodic fevers** in an endemic region suggesting a parasitic infection.
Question 12: A 19-year-old man is brought to the emergency department following a high-speed motor vehicle collision in which he was a restrained passenger. He complains of pelvic pain and urinary retention with overflow incontinence, along with associated lower extremity weakness. Examination shows perineal bruising and there is pain with manual compression of the pelvis. Injury to which of the following structures is most likely responsible for this patient's urinary incontinence?
A. Ilioinguinal nerve
B. Obturator nerve
C. Genitofemoral nerve
D. Pelvic splanchnic nerves (Correct Answer)
E. Superior gluteal nerve
Explanation: ***Pelvic splanchnic nerves***
- Urinary retention with overflow incontinence and lower extremity weakness following a pelvic trauma suggests damage to the **sacral spinal segments** or the **pelvic splanchnic nerves**.
- These nerves carry **parasympathetic fibers** that stimulate bladder contraction (detrusor muscle) and relaxation of the internal urethral sphincter, which are crucial for normal micturition.
*Ilioinguinal nerve*
- This nerve supplies sensory innervation to the **genitalia** and part of the inner thigh, and motor innervation to the internal oblique and transversus abdominis muscles.
- Damage to this nerve would primarily cause sensory deficits or abdominal muscle weakness, not urinary retention or lower extremity weakness.
*Obturator nerve*
- The obturator nerve primarily innervates the **adductor muscles of the thigh** and provides sensory innervation to the medial thigh.
- Injury would result in difficulty with hip adduction and sensory loss in the medial thigh, not bladder dysfunction or diffuse lower extremity weakness.
*Genitofemoral nerve*
- This nerve provides sensory innervation to the **anterior compartment of the thigh** and the external genitalia, and motor innervation to the cremaster muscle.
- Damage would typically manifest as altered sensation in these areas or an absent cremasteric reflex, without directly affecting bladder function.
*Superior gluteal nerve*
- The superior gluteal nerve innervates the **gluteus medius, gluteus minimus, and tensor fasciae latae muscles**, which are crucial for hip abduction and stabilization during walking.
- Injury would lead to a characteristic **Trendelenburg gait**, but would not directly cause urinary incontinence or retention.
Question 13: A 53-year-old multiparous woman is scheduled to undergo elective sling surgery for treatment of stress incontinence. She has frequent loss of small amounts of urine when she coughs or laughs, despite attempts at conservative treatment. The physician inserts trocars in the obturator foramen bilaterally to make the incision and passes a mesh around the pubic bones and underneath the urethra to form a sling. During the procedure, the physician accidentally injures a nerve in the obturator foramen. The function of which of the following muscles is most likely to be affected following the procedure?
A. Obturator internus
B. Tensor fascia latae
C. Adductor longus (Correct Answer)
D. Semitendinosus
E. Transversus abdominis
Explanation: ***Adductor longus***
- The **obturator nerve** passes through the obturator foramen and innervates the **adductor muscles** of the thigh, including the **adductor longus**.
- Injury to the obturator nerve would therefore directly affect the function of the adductor longus, leading to impaired thigh adduction.
*Obturator internus*
- The **obturator internus** muscle is innervated by the **nerve to obturator internus**, which arises from the sacral plexus (L5-S2).
- This nerve does not pass through the obturator foramen, making injury to this muscle unlikely in this specific scenario.
*Tensor fascia latae*
- The **tensor fascia latae** is innervated by the **superior gluteal nerve** (L4-S1).
- The superior gluteal nerve is located deeper in the gluteal region and does not traverse the obturator foramen.
*Semitendinosus*
- The **semitendinosus** is one of the hamstring muscles and is innervated by the **tibial division of the sciatic nerve** (L5-S2).
- The sciatic nerve is located posteriorly in the thigh and does not pass through the obturator foramen.
*Transversus abdominis*
- The **transversus abdominis** muscle is innervated by the **thoracoabdominal nerves** (T7-T11) and the **subcostal nerve** (T12).
- These nerves supply the abdominal wall and are anatomically distant from the obturator foramen, hence injury is not expected.
Question 14: A 60-year-old post-menopausal female presents to her gynecologist with vaginal bleeding. Her last period was over 10 years ago. Dilation and curettage reveals endometrial carcinoma so she is scheduled to undergo a total abdominal hysterectomy and bilateral salpingo-oophorectomy. During surgery, the gynecologist visualizes paired fibrous structures arising from the cervix and attaching to the lateral pelvic walls at the level of the ischial spines. Which of the following vessels is found within each of the paired visualized structure?
A. Vaginal artery
B. Superior vesical artery
C. Uterine artery (Correct Answer)
D. Artery of Sampson
E. Ovarian artery
Explanation: ***Uterine artery***
- The paired fibrous structures described are the **cardinal ligaments (transverse cervical ligaments)**, which contain the **uterine arteries** as they course towards the uterus.
- The uterine artery, a branch of the **internal iliac artery**, crosses over the **ureter** within the cardinal ligament—a critical anatomical relationship during gynecological surgery ("water under the bridge").
- This is the primary vessel within the cardinal ligament and the key vascular structure at risk during hysterectomy.
*Vaginal artery*
- The vaginal artery typically branches from the **uterine artery** or directly from the **internal iliac artery**, but it is not the main vessel found within the cardinal ligament.
- It primarily supplies the **vagina**, not contained within the cardinal ligament support structure.
*Superior vesical artery*
- The superior vesical artery supplies the **upper part of the bladder** and originates from the **umbilical artery** (a branch of the internal iliac artery).
- It is not anatomically associated with the cardinal ligament or uterine support structures.
*Artery of Sampson*
- The Artery of Sampson is a branch of the **uterine artery** that anastomoses with the **ovarian artery** within the **broad ligament**, not the cardinal ligament.
- It is a minor vessel involved in the dual blood supply to the ovaries and uterus, not a primary structure within the cardinal ligament.
*Ovarian artery*
- The ovarian artery originates directly from the **abdominal aorta** and travels within the **suspensory ligament of the ovary (infundibulopelvic ligament)**, not the cardinal ligament.
- It supplies the **ovaries and fallopian tubes**, with a trajectory that is anatomically distinct from structures within the cardinal ligament.
Question 15: A 56-year-old man comes to the clinic complaining of sexual dysfunction. He reports normal sexual function until 4 months ago when his relationship with his wife became stressful due to a death in the family. When asked about the details of his dysfunction, he claims that he is “able to get it up, but just can’t finish the job.” He denies any decrease in libido or erections, endorses morning erections, but an inability to ejaculate. He is an avid cyclist and exercises regularly. His past medical history includes depression and diabetes, for which he takes citalopram and metformin, respectively. A physical examination is unremarkable. What is the most likely explanation for this patient’s symptoms?
A. Testosterone deficiency
B. Autonomic neuropathy secondary to systemic disease
C. Psychological stress
D. Damage to the pudendal nerve
E. Medication side effect (Correct Answer)
Explanation: ***Medication side effect***
- The patient's inability to ejaculate while maintaining normal libido, erections, and morning erections is highly suggestive of **ejaculatory dysfunction** caused by the **citalopram**, a selective serotonin reuptake inhibitor (SSRI).
- SSRIs, like citalopram, are known to commonly cause sexual side effects, including **delayed ejaculation** and **anorgasmia**, by increasing serotonin levels, which can inhibit the ejaculatory reflex.
*Testosterone deficiency*
- Testosterone deficiency usually presents with **decreased libido**, **erectile dysfunction**, and a reduction in **morning erections**, which are not reported by this patient.
- While it can impact sexual function, the specific symptom of inability to ejaculate with preserved erections points away from low testosterone.
*Autonomic neuropathy secondary to systemic disease*
- **Autonomic neuropathy**, often seen in patients with **diabetes**, can lead to ejaculatory dysfunction, including **retrograde ejaculation**.
- However, the patient's normal erections and libido, along with the recent onset coinciding with a stressful event and medication use, make medication a more likely primary cause in this scenario.
*Psychological stress*
- **Psychological stress** can certainly contribute to sexual dysfunction, leading to decreased libido or erectile difficulties.
- However, the patient explicitly states his erections and libido are normal, and he only experiences an inability to ejaculate, which is less commonly the sole manifestation of stress.
*Damage to the pudendal nerve*
- **Pudendal nerve damage** typically results in issues with **erectile function**, sensation in the perineum, and potentially urinary or fecal incontinence.
- This patient's preserved erections and specific issue with ejaculation make pudendal nerve damage an unlikely primary cause.
Question 16: A 26-year-old woman presents to the obstetrics ward to deliver her baby. The obstetrician establishes a pudendal nerve block via intravaginal injection of lidocaine near the tip of the ischial spine. From which of the following nerve roots does the pudendal nerve originate?
A. L4-L5
B. S2-S4 (Correct Answer)
C. L3-L4
D. L5-S2
E. L5-S1
Explanation: ***S2-S4***
- The **pudendal nerve** originates from the **sacral plexus**, specifically from the ventral rami of spinal nerves **S2, S3, and S4**.
- Its origin from these segments is crucial for its function in innervating structures of the **perineum**, **external genitalia**, and the **anal and urethral sphincters**, making it highly relevant for procedures like **pudendal nerve blocks** during childbirth.
*L4-L5*
- Nerve roots **L4-L5** contribute significantly to the **lumbar plexus** and subsequently to nerves like the **femoral nerve** and portions of the **sciatic nerve**.
- These roots are primarily involved in innervating the **lower limbs** (e.g., quadriceps, tibialis anterior) and are not the primary origin of the pudendal nerve.
*L3-L4*
- The **L3-L4** nerve roots are also part of the **lumbar plexus**, chiefly contributing to the **femoral nerve**.
- They are essential for motor innervation of the **anterior thigh muscles** and sensation in this area, distinct from the pudendal nerve's role in the perineum.
*L5-S2*
- While **S2** is part of the pudendal nerve's origin, the inclusion of **L5** and **S1** primarily characterizes the origin of the **sciatic nerve** (which is formed by L4-S3) and its branches, such as the common fibular and tibial nerves.
- These roots are primarily concerned with the **posterior thigh** and **leg innervation**, not the perineum, which differentiates it from the pudendal nerve.
*L5-S1*
- The nerve roots **L5-S1** are key components of the **lumbosacral plexus** and contribute significantly to the **sciatic nerve**, particularly its innervation of the **hamstrings** and certain lower leg muscles.
- This origin does not align with the known roots of the **pudendal nerve** which stems from S2-S4.
Question 17: A 67-year-old man comes to the physician because of a 3-month history of difficulty initiating urination. He wakes up at least 3–4 times at night to urinate. Digital rectal examination shows a symmetrically enlarged, nontender prostate with a rubbery consistency. Laboratory studies show a prostate-specific antigen level of 2.1 ng/mL (N < 4). Which of the following is the most likely underlying cause of this patient's symptoms?
A. Lymphocytic infiltration of anterior prostatic lobe stroma
B. Hyperplasia of lateral prostatic lobe tissue
C. Infiltrating dysplasia of posterior prostatic lobe epithelium
D. Infiltrating neoplasia of bladder urothelium
E. Hypertrophy of middle prostatic lobe tissue (Correct Answer)
Explanation: ***Hypertrophy of middle prostatic lobe tissue***
- This patient's symptoms of **difficulty initiating urination** and **nocturia** are classic for **benign prostatic hyperplasia (BPH)**.
- The **middle lobe** enlargement is particularly significant because it can **protrude into the bladder neck**, directly causing **urethral obstruction** and the obstructive voiding symptoms seen here.
- The digital rectal exam finding of a **symmetrically enlarged, nontender prostate** with a **rubbery consistency** is characteristic of BPH.
- The **normal PSA level** (2.1 ng/mL) supports a benign process.
*Lymphocytic infiltration of anterior prostatic lobe stroma*
- **Lymphocytic infiltration** of the prostate is consistent with **prostatitis**, which would typically present with **pain, fever, and dysuria**, not just obstructive symptoms.
- The **nontender prostate** on examination argues against prostatitis.
*Hyperplasia of lateral prostatic lobe tissue*
- While **lateral lobe hyperplasia** (transition zone) is the **most common finding in BPH**, this option is less specific to the obstructive symptoms described.
- BPH typically involves both lateral and middle lobes, but **middle lobe** enlargement more directly causes **bladder outlet obstruction** by protruding into the bladder neck.
- Lateral lobe hyperplasia causes obstruction by compressing the prostatic urethra but is less likely to cause the severe obstructive symptoms without middle lobe involvement.
*Infiltrating dysplasia of posterior prostatic lobe epithelium*
- **Dysplasia** in the posterior lobe (peripheral zone) suggests a **premalignant condition** or **early prostate cancer**, which would more likely cause an **asymmetric, firm, or nodular prostate** on DRE.
- The **normal PSA** and **benign examination findings** do not suggest malignancy.
*Infiltrating neoplasia of bladder urothelium*
- **Bladder cancer** typically presents with **painless hematuria** as its primary symptom, which is not mentioned here.
- The **DRE findings** of prostatic enlargement point to prostatic, not bladder, pathology.
Question 18: A 55-year-old man comes to the physician because of a 2-day history of severe perianal pain and bright red blood in his stool. Examination shows a bulging, red nodule at the rim of the anal opening. Which of the following arteries is the most likely source of blood to the mass found during examination?
A. Inferior gluteal
B. Internal pudendal (Correct Answer)
C. Median sacral
D. Superior rectal
E. Deep circumflex iliac
Explanation: ***Internal pudendal***
- The **internal pudendal artery** is the primary arterial supply to the **perineum** and structures of the **anus**, including the external hemorrhoidal plexus via its **inferior rectal artery** branches.
- A **thrombosed external hemorrhoid**, presenting as a painful, bulging perianal nodule with bright red blood, receives its blood supply from branches of this artery.
- External hemorrhoids occur **below the dentate line** and are supplied by the internal pudendal system, distinguishing them from internal hemorrhoids.
*Inferior gluteal*
- The **inferior gluteal artery** primarily supplies the **gluteal muscles** and posterior thigh, not the perianal region.
- Injury to this artery typically results in deep buttock or thigh hematomas, not perianal bleeding.
*Median sacral*
- The **median sacral artery** originates from the aorta and supplies the posterior vertebral column and rectum but does not supply the **external hemorrhoidal plexus** or anal rim directly.
- Bleeding from this artery is rare and would typically be associated with deep retroperitoneal or sacral injury.
*Superior rectal*
- The **superior rectal artery** supplies the **proximal rectum** and contributes to the internal hemorrhoidal plexus, which involves internal hemorrhoids **above the dentate line**.
- The described mass is an **external hemorrhoid** at the anal rim, fed by the internal pudendal artery branches, not the superior rectal artery.
*Deep circumflex iliac*
- The **deep circumflex iliac artery** supplies the **abdominal wall** and iliac crest, not the perianal region.
- Bleeding from this artery would manifest as a hematoma in the flank or inguinal region.
Question 19: A 73-year-old man comes to the physician because of a 2-month history of intermittent blood in his stool. He has had no pain with defecation. Physical examination shows a 2-cm mass located above the dentate line. Further evaluation of the mass confirms adenocarcinoma. Which of the following describes the most likely route of hematogenous spread of the malignancy?
D. Superior rectal vein → inferior mesenteric vein → hepatic portal vein (Correct Answer)
E. Superior rectal vein → middle colic vein → hepatic portal vein
Explanation: ***Superior rectal vein → inferior mesenteric vein → hepatic portal vein***
- A mass located above the **dentate line** indicates a malignancy originating from the **superior rectum**. The venous drainage of this region is primarily via the **superior rectal vein**.
- The superior rectal vein drains into the **inferior mesenteric vein**, which then joins the **splenic vein** to form the **hepatic portal vein**, the most common route for **hematogenous spread** of colorectal cancers to the **liver**.
*Inferior rectal vein → inferior mesenteric vein → splenic vein*
- The **inferior rectal vein** drains the area below the **dentate line**, which is not the location of the described mass.
- While the destination (hepatic portal system via splenic vein) is suitable for liver metastasis, the origin (inferior rectal vein) is incorrect for a lesion above the dentate line.
*Inferior rectal vein → internal pudendal vein → external iliac vein*
- This pathway describes the venous drainage of the **anal canal below the dentate line**. The malignancy is located above the dentate line, rendering this route incorrect.
- This pathway would typically lead to systemic circulation through the **inferior vena cava**, not directly to the liver via the portal system.
*Inferior rectal vein → internal pudendal vein → internal iliac vein*
- This route originates from the **anal canal below the dentate line**, which is inconsistent with the tumor's location above the dentate line.
- The internal iliac vein drainage ultimately leads to the **inferior vena cava**, bypassing the hepatic portal system directly.
*Superior rectal vein → middle colic vein → hepatic portal vein*
- While the **superior rectal vein** is the correct origin, it drains into the **inferior mesenteric vein**, not the middle colic vein.
- The **middle colic vein** drains the transverse colon and empties into the superior mesenteric vein, not the inferior mesenteric vein.
Question 20: A 70-year-old woman comes to the physician for a follow-up examination 2 months after undergoing a total hip replacement surgery. She reports that she has persistent difficulty in walking since the surgery despite regular physiotherapy. Examination of her gait shows sagging of the left pelvis when her right leg is weight-bearing. Which of the following nerves is most likely to have been injured in this patient?
A. Left femoral nerve
B. Left superior gluteal nerve
C. Right superior gluteal nerve (Correct Answer)
D. Left inferior gluteal nerve
E. Right femoral nerve
Explanation: ***Right superior gluteal nerve***
- The **Trendelenburg sign**, characterized by the sagging of the contralateral hip when the affected leg is lifted, indicates weakness or paralysis of the **gluteus medius** and **minimus muscles**.
- These muscles are innervated by the **superior gluteal nerve**, and damage to the right superior gluteal nerve would cause the left hip to sag when the right leg is bearing weight.
*Left femoral nerve*
- Injury to the **femoral nerve** would primarily affect the **quadriceps femoris muscles**, leading to weakness in knee extension and possibly sensory deficits on the anterior thigh.
- It would not typically cause a **Trendelenburg gait**, which is specific to gluteal muscle weakness.
*Left superior gluteal nerve*
- Damage to the left superior gluteal nerve would cause the **right pelvis to sag** when the left leg is weight-bearing.
- The patient presents with sagging of the **left pelvis** when the **right leg** is weight-bearing, indicating a right-sided gluteal muscle weakness.
*Left inferior gluteal nerve*
- The **inferior gluteal nerve** primarily innervates the **gluteus maximus muscle**, which is responsible for hip extension.
- Injury would cause difficulty in climbing stairs or standing up from a seated position, but not typically the **Trendelenburg sign**.
*Right femoral nerve*
- Similar to left femoral nerve injury, damage to the right femoral nerve would result in weakness of the **right quadriceps femoris** and impaired knee extension.
- This injury does not explain the **Trendelenburg sign** observed in the patient.
