A 3D-printed condom intrauterine balloon tamponade: Design, prototyping, and technical validation

Abstract

Post-partum haemorrhage is among the main causes of (preventable) mortality for women in low-resource settings (LRSs), where, in 2017, the mortality ratio was 462 out of every 100 000 live births, over 10 times higher than for high-resource settings. There are different treatments available for post-partum haemorrhage. The intrauterine balloon tamponade is a medical device that proved to be a simple and cost-effective approach. Currently, there are several balloon tamponades available, with different design and working principles. However, all these devices were designed for high-resource settings, presenting several aspects that could be inappropriate for many lower-income countries. This paper presents the results of a preclinical study aiming at informing the design, prototyping and validation of a 3D-printed intrauterine balloon tamponade concept, contributing towards the United Nation's Sustainable Development Goal 3: Good health and Well-being. Frugal engineering concepts and contextualised design techniques were applied throughout, to define the design requirements and specifications. The performance of the final prototype was validated against the requirements of the UK National Health System (NHS) technical guidelines and relevant literature, measuring the water leak and pressure drop over time, both open air and in a approximate uterus model. The resulting prototype is made up of six components, some of which are easy to retrieve, namely a water bottle, a silicone tube and an ordinary condom, while others can be manufactured locally using 3D printers, namely a modified bottle cap, a flow stopper and a valve for holding the condom in place. Validation testing bore promising results with no water or pressure leak open air, and minimal leaks in the approximate uterus model. This demonstrates that the 3D printed condom-based intrauterine balloon tamponade is performing well against the requirements and, when compared to the state of the art, it could be a more appropriate and more resilient solution to low-resource settings, as it bypasses the challenges in the supply of consumables and presents a greener option based on circular economy.

Fig 1. The inflation of the system and the two tests, i.e., water leak tests and pressure drop tests, carried out in two conditions, i.e., open air and simulated working conditions.

Fig 2. The setup of the open-air experiments: The condom filled with water and the flow-stopper that prevents the water from flowing back through the tube.

Fig 3. The two positions of the uterus model during the water leak and pressure test.

Fig 4. The proposed mechanism of the intrauterine balloon tamponade in treating postpartum haemorrhage.

When the water reservoir is emptied into the condom balloon, the balloon becomes inflated, applying pressure inside the uterus.

Fig 5. The prototype system, with CAD images of parts for 3D printing: A-D valves of different design: A, rounded snap-fit valve, B, square snap-fit valve, C, fine threaded valve, D, coarse-threaded valve; E, modified bottle cap with plug and v seals, compatible with common soda bottles; F, flow stopper, a variety of globe valve preventing flow back of water down the tube.

Fig 6. The modified bottle cap with the plug and v seals.

Fig 7. The flow stopper, a variety of globe valve.

Fig 8. The uterus model.

Fig 9. The hourly water leakage for the 4 different types of valves.

Fig 10. Bland-Altman plot showing the 95% limits of agreement (red lines) with the 95% confidence interval (red region) and the bias (blue) with its 95% confidence interval (blue region).