Question 21: Which of the following is the process of breaking the clavicle during delivery?
- A. Cleidotomy (Correct Answer)
- B. Zavanelli manoeuvre
- C. Craniotomy
- D. Symphysiotomy
Explanation: ***Cleidotomy*** - This is a destructive obstetric procedure where the fetal clavicle is intentionally broken or cut to reduce the **bisacromial diameter**. It is utilized primarily in cases of severe, unrelieved **shoulder dystocia**, especially if the fetus has already succumbed (**Fetal demise**).
*Craniotomy* - This is a destructive procedure aimed at reducing the size of the **fetal head** by crushing or perforating the skull. It is performed when the fetal head is impacted and delivery is otherwise impossible, usually only if there is **fetal demise**.
*Symphysiotomy* - This procedure involves surgically incising the **fibrocartilage** of the **pubic symphysis** to widen the pelvic outlet. It is used to relieve **obstructed labor** due to minor cephalopelvic disproportion, allowing vaginal delivery.
*Zavanelli manoeuvre* - This is an emergency procedure for severe **shoulder dystocia** where the delivered fetal head is pushed back into the birth canal (**cephalic replacement**). It mandates immediate delivery via **Cesarean section** following the replacement.
Question 22: Which of the following is the best parameter for estimation of fetal age by ultrasound in 1st trimester?
- A. Crown rump length (Correct Answer)
- B. Biparietal Diameter
- C. Abdominal circumference
- D. Head circumference
Explanation: ***Crown rump length***
- The **Crown Rump Length (CRL)** is the most accurate parameter for estimating gestational age during the **first trimester** (up to 12 weeks of gestation).
- This is because biological variation between fetuses is minimal during early development, providing a narrow range of error (typically ±5-7 days).
*Biparietal Diameter*
- **Biparietal Diameter (BPD)** becomes the primary parameter for dating in the **second trimester** (after 12 weeks of gestation).
- Its accuracy in the first trimester is significantly lower than CRL due to difficulty in obtaining standardized measurements and higher potential for measurement variability.
*Head circumference*
- **Head circumference (HC)** is highly utilized, often alongside BPD, for fetal growth assessment and dating near the mid-to-late second trimester.
- Like BPD, HC is not the most precise measure for dating during the **first trimester** when CRL dominates.
*Abdominal circumference*
- **Abdominal circumference (AC)** is mainly used to assess **fetal weight** and growth, often becoming inaccurate for dating due to high biological variability later in gestation.
- It is the least accurate parameter for establishing gestational age in the **first trimester** compared to CRL, BPD, and HC.