Polyhydramnios or hydramnios means an increase in the amount of amniotic fluid. This condition leads to pregnancy complications in 1-2% of cases. Amniotic fluid is one of the most important components of the gestational sac in which the baby is located. This fluid plays a big role in ultrasound assessment of the normal physiology of pregnancy, especially in the second and third trimesters. The main contributors of amniotic fluid are renal urine production, swallowing, inspiration, and diffusion of the fluids via amniotic membranes. Polyhydramnios can cause suspicion at first, especially in normal pregnancies, when the uterus increases in size thus giving a larger-than-usual look to the womb. The uterus may feel more tense, and checking the baby's heartbeat may become difficult due to the fact that the voice is less audible.


Polyhydramnios is classified according to the excess of the amount of water to determine the risk group. The amount of AFI (Amniotic Fluid Index), measured on 4 quadrants by ultrasound, of 25-29.9 cm is considered mild polyhydramnios, of 30-34.9 cm is moderate polyhydramnios, and of 35 cm and above is classified as severe polyhydramnios. Mild polyhydramnios occurs in 2/3 of all cases and is the most common group. Moderate polyhydramnios accounts for 20% of all cases, and the severe group for 15%. When assessing polyhydramnios, the measurement of total amniotic fluid gives a safer result. In single pocket measurements, the deepest single pocket measurement of 8-9.9 cm is considered mild polyhydramnios; of 10-11.9 cm is moderate polyhydramnios, and 12cm and above is classified as severe polyhydramnios. According to the studies conducted when all these groups were compared, it was shown that severe cases of polyhydramnios were due to an underlying cause, while mild cases of polyhydramnios may not have any underlying cause.


When all risk groups were examined, 15% of the cases were due to fetal congenital anomalies, and 15-20% were related to diabetes mellitus. Among the rarer causes, fetal infections are also indicated. Among these infections, the most common ones are parvovirus, cytomegalovirus, toxoplasma, and syphilis infections. Polyhydramnios can also occur as a result of hydrops (water collection in the baby's body cavities). To mention congenital anomalies, central nervous system diseases such as anencephaly result in polyhydramnios due to obstruction of swallowing. Again, cases such as esophageal obstructions or duodenal (a part of the intestine) atresia, that is, insufficient development of the intestine, result in polyhydramnios. According to studies, as the degree of hydramnios increases, the risk of anomaly increases and reaches up to 30%. Baby's growth alongside polyhydramnios increases the risk of diabetes and growth retardation. The diagnosis of hydramnios in multiple pregnancies is made when the amount of amniotic fluid in the deepest single pocket is 8 cm or more.

Especially in monochorionic pregnancies, twin-to-twin transfusion syndrome should be kept in mind, if one baby has hydramniosis and the other has oligohydramnios (reduced water in infants), the necessary examinations should be performed. If no underlying cause for polyhydramnios is found after all these examinations have been performed, it is called idiopathic polyhydramnios and accounts for up to 70% of all cases. This condition can also be explained by the fact that the increased amount of amniotic fluid, which is mostly baby's urine, can be observed because older babies urinate more.


First of all, polyhydramnios can occur early, that is earlier than the 28th week, or in the late period. The risk of miscarriage and preterm delivery in polyhydramnios cases that started in the early period was found to be increased compared to those that started in the late period. Although polyhydramnios does not change the mode of delivery, especially when accompanied by diabetes, large babies, that is, babies weighing >4000gr, result in cesarean delivery. It has been found that polyhydramnios increases the likelihood of cesarean delivery by about 3 times. Polyhydramnios, which develops in the early stages, stresses other organs in the abdomen due to the size of the growing uterus, the mother feels more tense, and this condition can cause urinary symptoms, for example, by pressing on the bladder.

Regarding the circulatory system, edema may occur due to pressure on the vessels. In cases of severe respiratory distress of the mother, an appropriate amount of amniotic fluid can be taken in a procedure called amnioreduction. Its purpose is to normalize the level of amniotic fluid. In cases of polydidramniosis, some drugs that reduce the baby's urination can also be given to the mother, and these drugs pass from the mother to the baby through the placenta and have an effect on the baby. Such interventions are rarely applied today and can be called experimental, and are applied in the form of personalized planning.




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