Correct Answer: C

Rationale: The correct answer is C: Premature rupture of membranes. Oligohydramnios is a condition characterized by low levels of amniotic fluid which can be caused by the premature rupture of membranes, leading to the leakage of amniotic fluid. This condition can result in various complications such as fetal growth restriction and compression of the umbilical cord. Maternal hypertension (choice A) is not a direct cause of oligohydramnios. Multiple gestations (choice B) may lead to polyhydramnios (excessive amniotic fluid) rather than oligohydramnios. Fetal macrosomia (choice D) is associated with increased amniotic fluid levels rather than decreased levels seen in oligohydramnios.

Correct Answer: B

Rationale: The correct answer is B: Cephalopelvic disproportion. This condition occurs when the baby's head is too large to pass through the mother's pelvis during labor. This leads to obstructed labor, causing complications for both the mother and the baby. Maternal exhaustion (A) may occur as a result of prolonged labor but is not the primary cause of obstructed labor. Microsomic fetus (C) refers to a small baby and would not typically cause obstructed labor. Fetal exsanguination (D) is the loss of blood from the fetus and is not a common cause of obstructed labor. Cephalopelvic disproportion is the most common reason for obstructed labor as it directly affects the passage of the baby through the birth canal.

Correct Answer: D

Rationale: The correct diagnostic test for the patient is a barium enema. This test is commonly used to evaluate the colon and rectum for conditions such as colonic obstruction, inflammatory bowel disease, or colorectal cancer. In this case, the patient's presentation of left lower quadrant pain with a history of constipation and variable bowel habits suggests a possible colonic obstruction, which can be visualized through a barium enema. A CT scan with contrast may be helpful in some cases but may not provide as clear a view of the colon as a barium enema. CBC with WBC differential is a general blood test and would not directly aid in diagnosing colonic issues. Colonoscopy, while a valuable tool for evaluating the colon, may not be suitable for this patient initially due to the acute nature of the presentation and the need to first rule out a potential obstruction.

Correct Answer: B

Rationale: The correct answer is B: Rotational injury. Flexion-distraction injuries of the thoracolumbar spine are often caused by rotational forces that occur during accidents such as motor vehicle collisions or falls. These forces lead to the spine being twisted, causing separation of the vertebrae. Blunt trauma (A) can cause various spinal injuries but is not specific to flexion-distraction injuries. Seat belts (C) are designed to prevent spinal injuries by restraining the body during a collision. Gunshot wounds (D) can cause spinal cord injuries but are not commonly associated with flexion-distraction injuries of the thoracolumbar spine.

Correct Answer: D

Rationale: The correct answer is D, "All of the above." Fetal macrosomia, malpresentation, and pelvic abnormalities are all known causes of obstructed labor. Fetal macrosomia refers to a large baby, which can lead to difficulty in passing through the birth canal. Malpresentation occurs when the baby is not positioned optimally for delivery, such as breech or transverse positions. Pelvic abnormalities, such as a contracted pelvis, can impede the baby's passage during labor. Therefore, selecting option D is appropriate as it encompasses all the major causes of obstructed labor. Choices A, B, and C are not individually comprehensive enough to cover all potential causes of obstructed labor.