As of September 30, 2021 and December 31, 2020 the carrying values of our indefinite lived intangible assets were as follows (in thousands):

^aDuring the three and nine months ended September 30, 2021 we transferred $380,000 of PerClot related trademarks to Baxter as a result of the Baxter Transaction described in Note 2.

We monitor the phases of development of our acquired in-process research and development projects, including the risks associated with further development and the amount and timing of benefits expected to be derived from the completed projects. Incremental costs associated with development are charged to expense as incurred. Capitalized costs are amortized over the estimated useful life of the developed asset once completed. Our in-process research and development projects are reviewed for impairment annually, or more frequently, if events or changes in circumstances indicate that the asset might be impaired.

Based on our experience with similar agreements, we believe that our acquired procurement contracts and agreements have indefinite useful lives, as we expect to continue to renew these contracts for the foreseeable future. We believe that our trademarks have indefinite useful lives as we currently anticipate that our trademarks will contribute to our cash flows indefinitely.

We evaluate our goodwill and non-amortizing intangible assets for impairment on an annual basis during the fourth quarter of the year, and, if necessary, during interim periods if factors indicate that an impairment review is warranted. As of September 30, 2021 we concluded that our assessment of current factors did not indicate that goodwill or non-amortizing intangible assets are more likely than not to be impaired. We will continue to evaluate the recoverability of these non-amortizing intangible assets in future periods as necessary.

As of September 30, 2021 and December 31, 2020 our entire goodwill balance was related to our Medical devices segment.


	Medical Devices Segment
Balance as of December 31, 2020	$	260,061
Ascyrus acquisition		(942)
Revaluation of goodwill denominated in foreign currency		(6,678)
Balance as of September 30, 2021	$	252,441

Definite Lived Intangible Assets

The definite lived intangible balance includes balances related to acquired technology, customer relationships, distribution and manufacturing rights and know-how, patents, and other definite lived intangible assets. During the three and nine months ended September 30, 2021 we transferred $1.2 million of PerClot related distribution and manufacturing rights to Baxter as a result of the Baxter Transaction described in Note 2. As of September 30, 2021 and December 31, 2020 the gross carrying values, accumulated amortization, and approximate amortization period of our definite lived intangible assets were as follows (in thousands):


	Gross Carrying		Accumulated		Amortization
September 30, 2021	Value		Amortization		Period
Acquired technology	$	215,917	$	44,129	11	–	22	Years
Customer lists and relationships		31,192		9,248	13	–	22	Years
Distribution and manufacturing rights and know-how		10,068		3,933	5	–	15	Years
Patents		4,041		3,136			17	Years
Other		3,938		1,589	4	–	5	Years

	Gross Carrying		Accumulated		Amortization
December 31, 2020	Value		Amortization		Period
Acquired technology	$	222,182	$	36,091	11	–	22	Years
Customer lists and relationships		31,316		8,132	13	–	22	Years
Distribution and manufacturing rights and know-how		14,728		5,349	5	–	15	Years
Patents		3,966		3,113			17	Years
Other		3,453		1,073	4	–	5	Years

Amortization Expense

The following is a summary of amortization expense as recorded in General, administrative, and marketing expenses on our Condensed Consolidated Statement of Operations and Comprehensive Income (Loss) (in thousands):


	Three Months Ended				Nine Months Ended
	September 30,				September 30,
	2021		2020		2021		2020
Amortization expense	$	4,203	$	3,397	$	12,701	$	9,430

As of September 30, 2021 scheduled amortization of intangible assets for the next five years is as follows (in thousands):


	Remainder
	of 2021		2022		2023		2024		2025		2026		Total
Amortization expense	$	4,121		15,944		15,434		15,050		13,002		12,771	$	76,322