Fetal heart rate is an important indicator of fetal health. For this reason, significant resources have been employed adapting ultrasound machines for use in low-resource settings. However, for over a century doctors and midwives have successfully monitored fetal heart rate using a more basic method—a type of stethoscope known as the pinard horn.
This simple device can be made from wood, plastic or aluminum, and is inexpensive, portable and durable in comparison to ultrasound machines. On one end is a cone-shaped opening, which is placed on the pregnant abdomen. On the other is a flat surface, which is held to the ear. Sound is conducted from one end to the other through a hollow tube, which amplifies the sound of the heartbeat.
Use of this instrument requires practice to locate and correctly assess fetal heart rate, which can sometimes be obscured by ambient sounds or the position of the fetus. The sound is best heard over the fetus’ back beginning at 18-20 weeks of pregnancy, and has been described as subtle—like a muffled watch ticking, or like a vibration in the ear. According to the sound quality of the heartbeat, an experienced birth attendant is also able to determine the orientation of the fetus, which can help detect breech births. Though we know anecdotally that the Pinard Horn or ‘fetoscope’ is used in many low resource settings, overviews and studies of effectiveness are non-existent.
We have seen field reports including this report from Malawi and this from Uganda and in this basics of maternal and newborn care guide by JHPIEGO.
The device was invented in 1895 by French obstetrician Adolphe Pinard—a champion for modern perinatal care. Pinard was an advocate for providing adequate housing and nutrition for impoverished pregnant and post-partum women. He was also a proponent of breastfeeding, hygiene for preventing infection, and non-separation of mother and baby at birth. Today, these practices are part of routine perinatal care procedures.
In form and function, the pinard horn resembles the very first stethoscope developed in 1816 by René Laennec. Laennec’s stethoscope in turn was modeled on the ear trumpet, an early form of hearing aid that utilized a bell shape to collect and amplify sounds, and a long tube to direct sounds into the ear.
A more recent incarnation is the fetoscope, which combines the technology of the pinard horn and the conventional stethoscope. It relies on a flat bar that is held against the forehead of the listener. This helps direct the sound of the fetal heartbeat through the earpieces of the stethoscope.
We are very interested in any reports or studies comparing the Pinard Horn to electronic fetal monitoring.
The image in this post is from Flickr and is: "KITGUM, Uganda, Oct 20, 2009 -- Stella, the head midwife of the Pajimo Clinic in rural Kitgum, Uganda, uses a Pinnard Horn - a wooden listening device to listen to a baby's heartbeat. The expectant mother was rushed into the clinic where Stella and a two Army Reserve Soldiers with the 7225th Medical Support Unit helped her deliver a 5.5 lb. baby boy about 90 minutes later."