A 29-year-old G2P2 female gives birth to a healthy baby boy at 39 weeks of gestation via vaginal delivery. Immediately after the delivery of the placenta, she experiences profuse vaginal hemorrhage. Her prior birthing history is notable for an emergency cesarean section during her first pregnancy. She did not receive any prenatal care during either pregnancy. Her past medical history is notable for obesity and diabetes mellitus, which is well controlled on metformin. Her temperature is 99.0°F (37.2°C), blood pressure is 95/50 mmHg, pulse is 125/min, and respirations are 22/min. On physical examination, the patient is in moderate distress. Her extremities are pale, cool, and clammy. Capillary refill is delayed. Which of the following is the most likely cause of this patient’s bleeding?

Chorionic villi attaching to the myometrium

Chorionic villi invading into the myometrium

Placental implantation over internal cervical os

Chorionic villi attaching to the decidua basalis

Chorionic villi invading into the serosa

A 27-year-old woman, gravida 3, para 2, at 41 weeks' gestation is admitted to the hospital in active labor. Her pregnancy has been uncomplicated. Both of her prior children were delivered by vaginal birth. She has a history of asthma. Current medications include iron and vitamin supplements. After a prolonged labor, she undergoes vaginal delivery. Shortly afterwards, she begins to have heavy vaginal bleeding with clots. Her temperature is 37.2°C (98.9°F), pulse is 90/min, respirations are 17/min, and blood pressure is 130/72 mm Hg. Examination shows a soft, enlarged, and boggy uterus on palpation. Laboratory studies show: Hemoglobin 10.8 g/dL Hematocrit 32.3% Leukocyte Count 9,000/mm3 Platelet Count 140,000/mm3 Prothrombin time 14 seconds Partial thromboplastin time 38 seconds Her bleeding continues despite bimanual uterine massage and administration of oxytocin. Which of the following is the most appropriate next step in management?

Administer carboprost tromethamine

Immediately following prolonged delivery of the placenta at 40 weeks gestation, a 32-year-old multiparous woman develops vaginal bleeding. Other than mild asthma, the patient’s pregnancy has been uncomplicated. She has attended many prenatal appointments and followed the physician's advice about screening for diseases, laboratory testing, diet, and exercise. Previous pregnancies were uncomplicated. She has no history of a serious illness. She is currently on intravenous infusion of oxytocin. Her temperature is 37.2°C (99.0°F), blood pressure is 108/60 mm Hg, pulse is 88/min, and respirations are 17/min. Uterine palpation reveals a soft enlarged fundus that extends above the umbilicus. Based on the assessment of the birth canal and placenta, which of the following options is the most appropriate initial step in patient management?

Manual exploration of the uterus

A 30-year-old woman, gravida 2, para 1, at 42 weeks' gestation is admitted to the hospital in active labor. Pregnancy has been complicated by gestational diabetes, for which she has been receiving insulin injections. Her first child was delivered by lower segment transverse cesarean section because of a nonreassuring fetal heart rate. Her pulse is 90/min, respirations are 18/min, and blood pressure is 135/80 mm Hg. The fetal heart rate tracing shows a baseline heart rate of 145/min and moderate variation with frequent accelerations and occasional early decelerations. She undergoes an elective repeat lower segment transverse cesarean section with complete removal of the placenta. Shortly after the operation, she starts having heavy uterine bleeding with passage of clots. Examination shows a soft uterus on palpation. Her bleeding continues despite fundal massage and the use of packing, oxytocin, misoprostol, and carboprost. Her pulse rate is now 120/min, respirations are 20/min, and blood pressure is 90/70 mm Hg. Her hemoglobin is 8 g/dL, hematocrit is 24%, platelet count is 120,000 mm3, prothrombin time is 11 seconds, and partial thromboplastin time is 30 seconds. Mass transfusion protocol is activated and a B-Lynch uterine compression suture is placed to control her bleeding. Which of the following is the mostly likely cause of her postpartum complication?

Lack of uterine muscle contraction

Adherent placenta to myometrium

Infection of the endometrial lining of the uterus

A 34-year-old G5P5 woman gave birth to a healthy infant 30 minutes ago by vacuum-assisted vaginal delivery and is now experiencing vaginal bleeding. The placenta was delivered spontaneously and was intact upon examination. The infant weighed 5.2 kg and had Apgar scores of 8 and 9. No perineal tear or intentional episiotomy occurred. The patient has type 1 diabetes. She had good glycemic control throughout her pregnancy. She took a prenatal vitamin daily. Blood pressure is 135/72 mmHg, pulse is 102/min, and respirations are 18/min. Upon physical examination, the uterine fundus is soft and palpated 4 cm above the umbilicus. There are 3-cm blood clots on the patient’s bed pad. Which of the following is the next best step in management for the patient’s bleeding?

Perform uterine massage and administer oxytocin

Manually remove retained placental fragments

Perform uterine artery embolization

A 30-year-old woman, gravida 2, para 1, abortus 1, comes to the physician because of failure to conceive for 12 months. She is sexually active with her husband 2–3 times per week. Her first child was born at term after vaginal delivery 2 years ago. At that time, the postpartum course was complicated by hemorrhage from retained placental products, and the patient underwent dilation and curettage. Menses occur at regular 28-day intervals and previously lasted for 5 days with normal flow, but now last for 2 days with significantly reduced flow. She stopped taking oral contraceptives 1 year after the birth of her son. Her vital signs are within normal limits. Speculum examination shows a normal vagina and cervix. The uterus is normal in size, and no adnexal masses are palpated. Which of the following is the most appropriate next step in management?

Hysteroscopy with potential adhesiolysis

Measurement of serum FSH and LH concentrations

Measurement of antisperm antibody concentration

Estrogen/progestin withdrawal test

Risk factors for postpartum hemorrhage for USMLE Step 1: High-Yield OB/GYN Lessons

The '4 T's' - A Bloody Mess

📌 A mnemonic to systematically identify the cause of postpartum hemorrhage (PPH).

Category	Description & Risk Factors
Tone (Atony)	Failure of the uterus to contract adequately after birth. Accounts for ~80% of PPH cases. Risks: Uterine overdistension (macrosomia >4000g, multiple gestations, polyhydramnios), uterine muscle fatigue (prolonged or rapid labor, high parity), chorioamnionitis, and use of uterine relaxants (e.g., magnesium sulfate).
Trauma	Genital tract lacerations (cervical, vaginal, perineal), uterine rupture, or uterine inversion. Risks: Operative vaginal delivery (forceps, vacuum), precipitous delivery, fetal macrosomia, episiotomy, and malpresentation.
Tissue	Retention of placental fragments, membranes, or clots in the uterus, which prevents effective contraction. Risks: Placenta accreta spectrum, succenturiate placental lobe, prior uterine surgery (e.g., C-section, myomectomy), and mismanagement of the third stage of labor.
Thrombin	Pre-existing or acquired coagulopathy that impairs clot formation. Risks: Inherited bleeding disorders (e.g., von Willebrand disease) and acquired conditions like HELLP syndrome, disseminated intravascular coagulation (DIC), or severe preeclampsia. Abruptio placentae is a major trigger.

At-Risk Profiles - Code Red Flags

📌 Mnemonic: The "4 T's"

Tone (Atony): Uterine inability to contract. Accounts for ~80% of cases.
- Overdistended Uterus: Multiple gestation, macrosomia (>4000g), polyhydramnios.
- Uterine Muscle Fatigue: Prolonged labor, oxytocin augmentation, grand multiparity (>5 deliveries).
- Chorioamnionitis, myomas.
Trauma: Lacerations of the genital tract.
- Precipitous delivery, operative vaginal delivery (forceps/vacuum).
- Malpresentation, episiotomy.
Tissue: Retained placental fragments or membranes.
- Placenta accreta/increta/percreta.
- Succenturiate lobe, incomplete placental separation.
Thrombin: Coagulopathy (pre-existing or acquired).
- HELLP syndrome, severe preeclampsia, placental abruption.
- Inherited bleeding disorders (e.g., von Willebrand disease), DIC.

Clinical Vignettes

Atony Risk: A G5P4 patient with twins, whose labor was augmented with oxytocin for 14 hours, delivers two infants weighing 3900g and 4100g. Post-delivery, she experiences heavy bleeding with a soft, boggy uterus.
Trauma/Tissue Risk: A G1P1 undergoes a rapid, precipitous delivery. After the placenta is delivered, bleeding persists despite a firm, well-contracted fundus.
Thrombin Risk: A patient with severe preeclampsia develops HELLP syndrome and placental abruption, leading to disseminated intravascular coagulation (DIC) and uncontrolled postpartum bleeding.

⭐ In a patient with persistent bleeding but a firm, well-contracted uterus, you must suspect genital tract trauma and perform a thorough examination.

High-Yield Points - ⚡ Biggest Takeaways

Uterine atony is the #1 cause of PPH, driven by uterine overdistention (e.g., twins, polyhydramnios) or muscle fatigue from prolonged labor.

Retained placental tissue is a key risk, preventing the uterus from contracting effectively.

Genital tract trauma, especially from operative vaginal delivery (forceps, vacuum), is a common cause.

A history of PPH and grand multiparity (≥5 births) are significant predictors.

Consider coagulopathies (like HELLP syndrome) that impair normal clotting.

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