Scan technique ii

Indications for 2nd & 3rd trimester scanning

• Assigning dates
• Assessing foetal growth, amniotic fluid volume, foetal heart motion & foetal presentation.
• Assessing placental position & texture.
• For review of foetal anatomy
• To detect the presence of adenexal masses or cysts or uterine myomas

Scan technique

• Bi parietal diameter measurement of the foetal head –BPD
• BPD measurement is more accurate in the first trimester.
• BPD is the distance between the anterior & posterior tables of the skull.
• It is measured perpendicular to the mid line echo (falx)

 

Scan technique i

First trimester

Indications

• Bleeding after a POA
• Pain during pregnancy
• Pregnancy complicated by fibroid or ovarian cyst

 

Preparation
Scans are performed though the full bladder using a 5 MHtz curvilinear probe.

Indications for first trimester sonography 

• Localization of the GS –Intra uterine or Ectopic pregnancy
• Identification of foetal viability
• Anovular gestation
• Estimation of POG
• Assessment of multiple pregnancy, number of embryos chorionicity & amniocity

Normal anatomy of the placenta & foetus

Normal anatomy of the placenta

Saggital projection

Placenta appears as an echogenic structure separated from the anechoic liquor in anterior or posterior walls of the uterus either in the upper segment of the fundus or in the lower segment closer to the cervical os or covering the os

     

Coronal projection

Placenta appears in lateral, anterior or posterior walls

Transducer on ant abdominal wall   

                 

Descriptive terms

Transducer

Echogenic lesions reflect ultrasound waves & appear as bright white echoes. eg.gas, calculi, calcifications

Transducer

Hypoechoic lesions partly transmits ultrasound waves appear as intermediate echoes eg.soft tissues, masses

Obstetric hemorrhage

Causes of obstetric hemorrhage

Ante partum

• Ectopic pregnancy
• Abortion
• H mole
• Placenta praevia
• Placental abruption

Intra partum and post partum

• Placenta praevia
• Previous caesarian section with placenta praevia
• Placental abruption
• Placenta accrete
• Uterine rupture
• Uterine atony
• Over distended uterus
• Retained products of conception
• Genital tract injury
• Broad ligament tear