A multigravida with previous 2 normal deliveries presents with unstable lie of the fetus at 34 weeks gestation. What could be the most probable cause?
**Core Concept**
The unstable lie of the fetus in a multigravida at 34 weeks gestation could be due to uterine anomalies or changes in the uterine shape, which can lead to malpresentation. This can be attributed to a condition known as uterine fibroids, which are benign tumors that can cause distortion of the uterine cavity.
**Why the Correct Answer is Right**
Uterine fibroids are the most common cause of malpresentation in multigravidas. They can cause the uterus to become irregular in shape, leading to an unstable lie of the fetus. This is because fibroids can grow within the uterine cavity, distorting its normal shape and potentially causing the fetus to become malpositioned. The growth of fibroids can also lead to an increase in the uterine size, which can further contribute to malpresentation.
**Why Each Wrong Option is Incorrect**
**Option A:** While previous uterine surgery can lead to uterine anomalies, it is not the most probable cause of unstable lie at 34 weeks gestation in a multigravida with previous normal deliveries.
**Option B:** Uterine anomalies are a possible cause of malpresentation, but they are less common than uterine fibroids in multigravidas.
**Option C:** Placenta previa is a condition where the placenta covers the cervical os, but it is not typically associated with unstable lie of the fetus.
**Option D:** While multiple gestations can cause malpresentation, this patient is a multigravida with a single fetus, making this option incorrect.
**Clinical Pearl / High-Yield Fact**
A key clinical pearl to remember is that uterine fibroids are a common cause of malpresentation in multigravidas, especially in the third trimester. It is essential to consider this diagnosis in patients with an unstable lie or malpresentation, particularly if they have a history of previous normal deliveries.
**Correct Answer:** C. Uterine fibroids.