DATING OF PREGNANCY FROM THE SYMPHYSIO-FUNDAL HEIGHT

CONTENT

-INTRODUCTION

-SFH AND PREGNANCY DATING

-DRAWBACKS

 

INTRODUCTION

The symphysiofundal height (SFH) refers to the measurement of the uterus from the uppermost part of your womb (i.e the fundus) to the top of your pubic bone in the midline, i.e the pubic symphysis. Routinely checked during the antenatal clinic for the monitoring of the fetal growth, the days of relying solely on the fundal height for dating pregnancy have gone thanks to the advent of  the ultrasound scan.

 

SFH AND PREGNANCY DATING

In general, the SFH often coincides with the age of the pregnancy in weeks ( +/- 2 to 3 weeks), the serial monitoring of the which can be used to monitor the growth pattern of a baby through out the antenatal clinic starting from booking till term. Any marked deviation from the expected normal increase in the SFH as the pregnancy advances, may suggest an abnormal growth pattern of the unborn baby, which may then require further investigations to determine the discrepancies. Hence, the SFH remains useful for providing a good perspective of the growth pattern of an unborn baby as well as a fairly good idea of how big or small the unborn baby is?

Secondly, various landmarks on a pregnant abdomen corresponds to a particular fundal height which can then be used to estimate the age of a pregnancy. For example, a pregnancy corresponds to about 12 weeks of pregnancy when the fundal height is felt at the pubic symphysis, to 20 - 22 weeks  of pregnancy when it is felt at the umbilicus and to about 36 weeks of pregnancy when it is felt at the xiphisternum. As the fetus gets older beyond 36weeks of age, the fundal height may get higher or lower depending on the descent of the head of the baby into the pelvic cavity and or the size of the baby. 

                 Symphysio-fundal height

 

DRAWBACKS

1.  The SFH becomes grossly inaccurate in the presence of uterine fibroids, multiple pregnancies (twins and triplets), polyhydramnious and the presence of large suprapubic and abdominal fat.

2.  At term, the SFH can not be solely relied upon for growth monitoring as a little variation in the fundal height may correspond to a large range of gestational age as such, making it difficult to pick abnormal growth patterns especially in cases of suspected IUGR.

3.  It is impossible to diagnose post term pregnancy with the use of SFA in women who present for the first time at or after term..

 

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