Correct Answer: A

Rationale: The correct answer is A: Six hours postnatally. Cephalohematoma is a collection of blood between a baby's skull and the periosteum. It typically appears several hours after birth due to trauma during delivery, causing bleeding under the periosteum. This allows time for the blood to accumulate and form a distinct swelling, making the onset around six hours postnatally. Choices B, C, and D are incorrect as they do not align with the typical timeline for the development of cephalohematoma.

Correct Answer: D

Rationale: Step 1: Atony of the uterus is the most common cause of primary postpartum hemorrhage due to inadequate uterine contractions. Step 2: Trauma of the genital tract can lead to bleeding but is not as common as atony of the uterus in postpartum hemorrhage. Step 3: Blood coagulation disorder can contribute to excessive bleeding but is not the primary cause of postpartum hemorrhage. Step 4: Prolonged 3rd stage can result in postpartum hemorrhage but is typically secondary to uterine atony.

Correct Answer: A

Rationale: The correct answer is A because cord presentation occurs when the umbilical cord lies in front of the presenting part after the membranes have ruptured. This can lead to compression of the cord during labor, affecting fetal oxygenation. Option B is incorrect as it describes cord prolapse, where the cord lies in front of the presenting part before membrane rupture. Option C describes nuchal cord, where the cord is wrapped around the fetal neck. Option D describes cord abruption, where the cord detaches prematurely from the placenta.

Correct Answer: A

Rationale: The presenting diameter in brow presentation is the submentobregmatic diameter. This is because in brow presentation, the fetal head is partially extended, causing the forehead (bregma) to be the presenting part. The submentobregmatic diameter is the distance between the chin (mentum) and the highest point of the forehead (bregma). This diameter is crucial for successful delivery in brow presentation as it is the smallest diameter that must pass through the maternal pelvis. Summary of other choices: B: Suboccipitofrontal - This diameter is not relevant in brow presentation as it involves the back of the head. C: Occipitalfrontal - This diameter is the distance between the back of the head and the forehead, also not relevant in brow presentation. D: Mentovertical - This diameter is the distance between the chin and the vertex of the head, not the forehead.

Correct Answer: A

Rationale: The correct answer is A: Six hours postnatally. Cephalohematoma is a collection of blood between a baby's skull and the periosteum. It typically appears several hours after birth due to trauma during delivery, causing bleeding under the periosteum. This allows time for the blood to accumulate and form a distinct swelling, making the onset around six hours postnatally. Choices B, C, and D are incorrect as they do not align with the typical timeline for the development of cephalohematoma.