Placenta pathology lab-carpenter-01.04.12

Discussion Slides

Case 1

•  A 40-year-old gravida 2 para 1 woman presented in active labor after an uncomplicated pregnancy and adequate prenatal care. (“Gravida” refers to the number of pregnancies and “para” refers to parity, the number of births. This is often abbreviated “G2 P1”. After the baby is born, the designation will be changed to G2 P2 if the baby is born, or G2 P1 Ab1 if there is a stillbirth.) The infant was born by normal spontaneous vaginal delivery (abbreviated NSVD) and Apgar scores are an estimate of the baby’s health at birth, and ranges from 0 for a baby born dead to 10 for a very healthy infant.) The baby was taken to the newborn nursery and the placenta was retained for possible examination.

Placentas should be sent to pathology if any of the conditions discussed in lecture are suspected, if there is a history of spontaneous abortions in the mother, if the baby goes to the Neonatal intensive care unit, if there is an abnormality in the baby, a history of maternal diabetes, or if the estimated gestational age of the baby is less than 36 weeks. The placentas in your lab reflect some of the findings possible in a case such as the one described above.

Exercise 1: Locate all of the gross structures listed in Fig. 1 in the core notes.

Describe any abnormalities present. If you have a twin placenta, locate the dividing membranes and determine what type of twinning is present.

Exercise 2: Locate all the structures listed in Fig. 2 C, and together with the gross placentas, describe the blood flow between mother and fetus.

Case 2

CASE TWO

•  Clinical Summary: The patient is a 28-year-old G2 P1 presenting in labor at 42 weeks gestation. The patient received adequate prenatal care and the pregnancy was unremarkable. Spontaneous rupture of membranes occurred, revealing a thick, dark green, slimy material in the amniotic fluid. Delivery progressed rapidly and fetal monitoring revealed severe fetal distress. The Apgar score of the infant at 1 minute was 1, and suction of the oropharynx was performed. A similar greenish material was noted, and vigorous resuscitation was performed. The infant was intubated, but remained cyanotic and bradycardic. The baby died and an autopsy was performed. No congenital abnormalities were noted. Examination of the lungs revealed a dark red cut surface, and abundant green mucus in the bronchi. The first slide of case 2 shows a bronchus distended by squames, which are part of the normal amniotic fluid. Because of the distress in utero the fetus inhaled an increased amount of fluid, so more squames than normal are seen in the lung. Some of the macrophages in the lung appeared to contain greenish pigment.

•  Question 1: •  What is the green material described

above? Where did it originate?

•  Question 2: •  Why did the baby die?

Gross Pathology: The gross placenta is seen in the next slide. The underlying cotyledons do not show any gross abnormalities.

Question 3: What is the most important gross finding?

Microscopic: The next slide shows a section of the fetal membranes. The pathologic findings in this placenta are seen only along the fetal

surface of both the membranes and the placenta itself. The amnion is occasionally interrupted by small clumps of eosinophilic material. This material may be the size of two or three cells. In the connective tissue immediately below the amnion, there are numerous macrophages. At high power, one can see that the macrophages have phagocytized granular, golden-tan pigment.

Question 4: What do you think is the nature of this pigment?

Question 5: Usually, these macrophages are only seen in the amnion and

underlying connective tissue. What do you think is the significance of the pigmented macrophages when they are present deep within the chorion?

Case 3

CASE THREE •  The mother is a 26-year-old G2 P1 O+, rubella immune,

VDRL nonreactive woman with spontaneous rupture of membranes after approximately 32 weeks gestation. Ultrasound showed that the fetus was in a breech position. An emergency cesarean section was done for fetal distress. The baby was born limp and cyanotic with a heart rate of less than 100 and no spontaneous respirations. Apgar scores were 1 at 1 minute and 6 at 5 minutes. Resuscitative measures were instituted and the baby was placed in the neonatal intensive care unit (NICU). The baby continued to do poorly with unstable vital signs. Life support was withdrawn and the patient died on the second day of life.

•  An autopsy was performed on the infant, and the major findings were within the lungs. Grossly, the lungs were heavy, consolidated and dark purple-red. A photomicrograph of the lungs is shown in the first 2 slides of case 3.

Question 1: What are the important findings in the first

slide? Question 2: What are the important findings in the

second slide? Placental Pathology: The major gross finding was thick, opaque

fetal membranes with a foul odor.

Placental Surface Bacteria

Microscopic pathology: Photomicrographs of the fetal surface of the placenta including a blood

vessel in the chorion are seen in slides 3 through 6 of case 3.

Question 3: What is the major microscopic feature in the first of the three slides?

Question 4: What is common to both the placental surface and lungs?

Question 5: What is the likely explanation for the premature rupture of membranes?

Question 6: Can you explain the correlation between the fetal pneumonia and the

chorioamnionitis?

Question 7: What is the mechanism of bacterial infection in most cases of

chrioamnionitis?

Fetal Lung Injury •  Normal – No injury

–  Fetus normally inspires amniotic fluid in utero •  Ascending Vaginal Bacterial Infection

–  Chorioamnionitis – Inflammation of Fetal Membranes –  Membrane Proteolysis and Premature Rupture

•  Fetal Prematurity –  Bacterial Infection of Amniotic Fluid

•  Fetal Pneumonia- Infection

•  Meconium Aspiration –  Premature Meconium Passage From Fetal GI Tract –  Inspiration of Meconium-contaminated Amniotic Fluid

•  Fetal Pneumonia - Chemical