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Abstract
Placenta is a Latin word mains circular cake. At term placenta is discoid in shape 15- 20 cm in diameter, 2.5cm in thickness and weighting about 500 gms, with fetal surface covered with Amnion and maternal surface showing 15- 20 cotyledons .
Placenta normally implanted to the upper uterine segment, 60 % in the post wall and 40 % in the anterior wall.
Placenta previa is one of placental abnormalities in which implantation of placenta occur in the lower uterine segment, below fetal presenting part.
Incidence of placenta previa is one in 200 to 250 and become higher at one in 20 in grand multipara. Incidence is also increased in cases with a prior uterine scar (e.g. Cesarean, myomectomy) (Faiz and Ananth, 2003).
Four degree of placenta previa have been recognized which (placenta previa lateralis, marginalis, incomplete centeralis, and complete placenta previa centeralis).
Abnormal placental invasion into the myometrium is potentially serious complication and according to degree of invasion different types was recognized.
Placenta accreta in which placenta becomes adherent to the myometrium, placenta increta which invades the myometrium, placenta percreta which penetrates the myometrium and becomes adherent to surrounding structures (Frederiksen, 1999).
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The combination of placenta previa and prior cesarean delivery reportedly increases the risk for myometrial invasion which attributed to the trophoblstic tissue invading along the surgical scar (Clark et al., 1972).
Placenta previa and myometrial invasion may necessitate cesarean hysterectomy and can be complicated by massive hemorrhage.
Placenta previa or placental myometrial invasion may be diagnosed during pregnancy in routine flow up or when complicated and may be accidentally discovered during labor
Diagnosis of placenta prevea or myometrial invasion prior to delivery allows the surgical team anticipates and plan for potential bleeding complications including possible prophylactic Balloon catheter and transfusion therapy preparations that may help reduce the associated maternal and fetal morbidity and mortality(Mitty et al., 1993).
Sonography is a common accurate method for diagnosis of placenta previa and myometrial invasion sonographic finding associated with placental invasion have been described by many authors
( Lerner et al ., 1995 ).
Specific songraphic criteria for invasion have been suggested by
(Finberg and Williams., 1992).These criteria include:
1- Loss of normal hypoechoic retroplacental myometerial zone.
2- Thinning or disruption of the hypoechoic uterine serosa-Bladder interface.
3- Presence of focal exophtic masses.
Large placental sonolucencies have been reported to be risk factor (Guy et al., 1990).
Doppler ultrasound is a non invasive method of studying the flow velocity because fetal maternal and placental circulation can be studied.
Color Doppler also allows the investigator to be caution of the correct vessel and allows detection of small vessels (Schulmen, 1994).
Color flow mapping predicated mymoetrial invasion when the smallest myometrial thickness was < 1 mm and large intraplacental lakes were demonstrated (Diane et al., 2000).
Although ultrasound findings with myometrial invasion have been described no large prospective serious that uses Doppler color flow mapping (CFM) to detect placental invasion has been reported (Diane et al., 2000).
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Aim of Work
The aim of this study is to evaluate the use of Color flow mapping CFM in pregnant women with placenta previa to predict myometeial invasion.