Patient's question:
I was pregnant for 7 months last year when I had a 4D ultrasound and found that the fetus had severe pulmonary edema and excessive amniotic fluid. What could be the cause of this?Follow-up question: I have had an abortion, and now I want to get pregnant again. What should I pay attention to or what tests should I undergo?
Doctor's answer:
Hello:Amniotic fluid volume increases gradually from the early stages of pregnancy and begins to decrease in the last four weeks. In full-term pregnancy, the amount of amniotic fluid is approximately 1000-1500ml. If the amniotic fluid exceeds 2000ml at any stage of pregnancy, it is referred to as polyhydramnios. Slowly increasing amniotic fluid is called chronic polyhydramnios, while a rapid increase in a short period is termed acute polyhydramnios. Polyhydramnios is more common in cases of fetal malformations, twins, diabetes, and maternal-fetal blood type incompatibility, among others.
### Common Causes
The exact cause has not yet been fully clarified. The main causes include:
- Idiopathic polyhydramnios, accounting for 30%-40% of cases, with the cause remaining unknown.
- Fetal malformations leading to polyhydramnios, accounting for about 25%, with central nervous system abnormalities and upper gastrointestinal tract malformations being the most common.
- Multiple pregnancies, where polyhydramnios is 10 times more frequent than in single pregnancies.
- Maternal-fetal blood type incompatibility, causing villous edema and affecting maternal-fetal fluid exchange.
- Diabetic pregnant women, where excessive fetal glucose leads to polyuria.
### Clinical Manifestations
- Chronic polyhydramnios develops slowly, and the pregnant woman adapts relatively well, with mild symptoms. However, when the uterus is highly distended, compression symptoms may still occur.
- Acute polyhydramnios often causes severe compression symptoms. The main symptoms include:
- Abdominal distension and pain, digestive disorders.
- Elevated diaphragm and heart displacement, affecting cardiopulmonary function, leading to shortness of breath, palpitations, and rapid pulse, making it difficult to lie flat.
- High abdominal pressure and venous (venous return obstruction), resulting in edema of the external genitalia and lower limbs, and varicose veins.
- Due to excessive uterine tension, premature labor is more likely, and preeclampsia often coexists.
- When membranes rupture, a sudden outflow of large amounts of amniotic fluid can cause the uterus to shrink rapidly, potentially leading to placental abruption.
- The umbilical cord may be expelled with the amniotic fluid, causing cord prolapse.
- Postpartum hemorrhage may occur due to uterine atony.
Abdominal Examination:
- Tense abdominal wall, shiny skin, and abdominal distension significantly larger than the gestational age.
- Fundal height and abdominal circumference are greater than normal in pregnancy.
- Palpation reveals fluid (fluid shivering), abnormal fetal position (often difficult to determine), distant or inaudible fetal heart tones, and a clear floating sensation of the fetal head.
### Diagnostic Methods
- Medical history, symptoms, and physical signs as described above.
- Ultrasound to detect abnormal amniotic fluid levels (>7cm average depth) or malformations/multiple pregnancies.
- X-ray (abdominal plain film, amniotic sac contrast, fetal contrast).
- Amniotic fluid AFP testing: Elevated AFP levels in cases of NTDs, upper gastrointestinal atresia, or polycystic kidneys.
### Specific Strategies
The management of polyhydramnios primarily depends on whether the fetus has malformations and the severity of maternal symptoms.
- If the fetus is normal and symptoms are mild, pregnancy can continue.
- Rest, low-sodium diet, and diuretics such as hydrochlorothiazide (25mg, three times daily) or traditional Chinese medicine for strengthening the spleen, promoting diuresis, and warming yang.
- In recent years, indomethacin (2.2-3.0mg/kg/day, a prostaglandin synthase inhibitor) has shown good efficacy.
- Amniocentesis may be performed to reduce amniotic fluid if necessary, alleviating compression symptoms.
- If the fetus has malformations, pregnancy should be terminated.