Placental examination at delivery

The utility of histopathological examination of the placenta and umbilical cord after delivery is directly relevant to many different aspects of perinatology from the epidemiology of specific obstetric complications to malpractice litigation.

The macroscopic examination of the placenta starts in the de­livery room with identification of placental and membranes com­pleteness and the number of vessels in the umbilical cord. This examination is performed by the midwife and/or birth attendant to alert the clinicians to possible retention of placental tissue in utero and undetected fetal anomalies associated with the SUA. A complete macroscopic report should also include placental weight as the evalu­ation of placenta-to-birth weight ratio or fetal-to-placental weight ratio (FPR) provides indirect information on placental development and function during pregnancy. An abnormal FPR has been shown to be a good predictor for short- and long-term adverse outcome during childhood and adulthood such as cardiovascular diseases (51, 75). In cases of multiple gestation pregnancy, labelling of pla­centas and umbilical cords, using different sizes or forms of clips, is essential for further investigations. The identification of structure of intertwin membranes in twins, site of insertion and number of ves­sels in each umbilical cord, and evaluation of vascular anastomoses in monochorionic twins can also be clinically useful (54).

The microscopic examination is performed in the laboratory by a specialist fetoplacental pathologist. The Amsterdam Placental Workshop Group has recently proposed a classification of placental lesions (76). This classification covers clinically significant micro­scopic placental lesions, which cannot be diagnosed antenatally.